Maternity & Nursing Bra Calculator
Pregnancy and nursing change your body. Enter your measurements and stage to get a comfortable, supportive bra size for your changing shape. Compare US, UK, EU, AU, and FR sizing.
Maternity & Nursing Bra Finder
Measure snugly under your bust – maternity bras should be comfortable but supportive.
Measure around the fullest part of your chest – don't compress tissue.
Select your current stage – this helps recommend the right style and support level.
34D
34D
75D
12D
90D
Need a different method? Try the Standard Bra Size Calculator or Sister Size Finder.
Why Maternity & Nursing Bras Are Different
During pregnancy and nursing, your breasts change significantly. They become larger, heavier, and more sensitive. A good maternity or nursing bra provides:
- Support without underwire – underwire can compress milk ducts and cause discomfort.
- Extra cup room – your breasts grow during pregnancy and engorge during nursing.
- Easy nursing access – clip-down cups or drop cups for feeding.
- Soft, breathable fabric – cotton blends reduce irritation.
How to Measure for a Maternity Bra
📏 1. Underbust (Band)
Wrap the tape snugly around your ribcage, just under your bust. Take the measurement after you exhale. Maternity bands should be comfortable – not too tight.
Tip: Consider going up one band size for later pregnancy.
📐 2. Bust (Cup)
Measure around the fullest part of your bust – usually across the nipples. Keep the tape level and don't pull it tight. This gives you your cup letter.
Tip: Size up in the cup for nursing – milk production can increase volume.
Stage-by-Stage Guide
🤰 First Trimester
Breasts may feel tender and start growing. Look for soft, wire-free bras with adjustable straps. Stick to your usual size or go up one cup.
🤱 Second Trimester
Significant growth. Look for maternity bras with extra cup room, wide straps, and multiple hook rows. You may need to size up in both band and cup.
👶 Third Trimester
Full growth – breasts are at their largest. Look for nursing bras with easy access clips. Size up in the cup and band for comfort.
🍼 Nursing/Postpartum
Breasts can fluctuate in size between feedings. Look for stretchy cups that accommodate changes, with drop-down or clip access for feeding.
Maternity Bra Size Guide
| Your Size | First Trimester | Second Trimester | Third Trimester | Nursing |
|---|---|---|---|---|
| 34B | 34B | 34C | 34D | 34D |
| 34C | 34C | 34D | 34DD | 34DD |
| 34D | 34D | 34DD | 36DD | 36DD |
| 36C | 36C | 36D | 36DD | 36DD |
| 36D | 36D | 36DD | 38DD | 38DD |
| 38C | 38C | 38D | 38DD | 38DD |
* These are general recommendations – individual changes vary. Always try on before buying.
Looking for sister sizes?
Try the Sister Size CalculatorFrequently Asked Questions
Should I size up in maternity bras?
Most women go up 1-2 cup sizes during pregnancy and nursing. Your band may also increase due to ribcage expansion. Measure every trimester for the best fit.
What's the difference between maternity and nursing bras?
Maternity bras are designed for pregnancy – soft, supportive, and wire-free. Nursing bras have the same features but also include clips or drops for easy breast access during feeding.
Can I wear underwire during pregnancy?
Most experts recommend avoiding underwire during pregnancy and nursing as it can compress milk ducts and cause discomfort or mastitis. Choose wire-free styles for comfort.
Does IMRango store my measurements?
No. Everything runs locally in your browser. We do not collect, store, or share any of your personal data or measurements.